This invention relates to improvements in the construction of diffusers used with centrifugal compressors. Of particular concern are diffusers used in aircraft gas turbine engines. In these engines it is common practice to use a high pressure ratio compressor which delivers a compressible fluid, usually air, at high velocity to a diffuser wherein the fluid is decelerated to produce a pressure rise.
Many different types of diffusers have been built for use in aircraft gas turbine engines. U.S. Pat. No. 3,333,762 by Vrana describes a pipe diffuser capable of operating over a wide range of pressure rise through the compressor. U.S. Pat. No. 3,420,435 by Jarosz discloses means for overcoming the disadvantages of the complex construction exhibited when building diffusers according to the teachings of Vrana. Jarosz shows how tube sections of expanding cross section can be easily bent at their outward ends to redirect the compressed fluid in a direction generally parallel to the impeller axes. U.S. Pat. No. 2,967,013 by Dallenbach discloses an approach for taking supersonic flow into account. Leading edge profiles of the diffuser vanes are configured such that shock waves do not occur since they are relieved in the regions where the gas flow is supersonic.
My invention expands on the knowledge disclosed in the above-referenced patents. Test results show that a diffuser built according to the teachings of my invention has lower losses, hence greater efficiency, than is the case with previous designs.